Complex biological systems are composed of many individual units (e.g. cells,molecules) that interact on a local level to produce global changes. Individuals in the system often rely on local information that reflects the global needs of the system to take an appropriate action. Complex systems have properties that are emergent, i.e. that cannot be explained by examining the individual units alone. Therefore, to comprehensively understand the basic principles operating behind complex biological systems, a more integrated approach is necessary. The purpose of this research is to study the following question: how do individuals in complex biological systems use local information to assess the global needs of the system? I will examine this question using a comparative model system: the chemical control of social behavior in a social insect, the harvester ant (Pogonomyrmex barbatus). Ant colonies act as complex biological systems; they lack any hierarchical control and changes in social behavior result from changes in individual behavior. Individual ants use chemically mediated interactions, in part, to assess the global needs of the colony. Specifically, I propose to: 1) use a behavioral bioassay to determine which class of chemicals mediates a measurable social behavior, task allocation, 2) purify and identify the compounds involved and 3) examine how the chemical signal changes with age and changes in behavior. This purpose of this research is to provide data that will add to understanding of the basic rules operating behind complex biological systems.